Colleague altering his parts

[changingnameforthis1234]

I have a fairly new work colleague. It's a small office and we are allowed a maximum of two at a time in there due to Covid and also wear masks as we can't really keep 2 metres apart. There are often three on duty for an hour in the middle of the day and then one of us takes a break outside.
My AIBU is that every single time I'm alone with this male colleague which isn't that often, he spreads his legs and sort of alters his bits. It's hard not to be aware and im finding it uncomfortable.
The organisation is very tough on any sort of behaviour that could cause offence. Problem is I really really don't know if this is just a habit he has or if he does it in front of any male colleague.
If I mention it to another colleague and ask it's very likely they would report it to the manager.
I'm really not sure if this is being done to intimidate, is habit, or he's just a skank. He's a male in his 40's. I'm older and female. He seems ok in other ways , certainly not objectionable in any other way
So AIBU to just continue to ignore?
Btw I've name changed and do promise I'm not trolling

In the first instance, why not challenge him with, "George, I won't talk to you while you're jiggling yourself like that. You need to sort yourself out privately somewhere else and come back to the office and we'll resume the work discussion when you're comfortable and can behave professionally and sit appropriately."

No please or thank you required, just firm instructions for what is acceptable professional behaviour in your presence.

This could easily be someone with a bad back settling into a chair. The OP has decided it's about his genitals but there's nothing to indicate it is. He's not touching them. He's shuffling about in the chair. Why now just say 'is your back bothering you?'. It's an easy way to bring attention to it and find out what's going on. I really can't imagine going to HR over a man shifting about in a chair and claiming you know it's his bits he's shifting. My back hurts and I often shift about in a chair and it has nowt to do with my fanny!

@TicketyTickTock

This could easily be someone with a bad back settling into a chair. The OP has decided it's about his genitals but there's nothing to indicate it is. He's not touching them. He's shuffling about in the chair. Why now just say 'is your back bothering you?'. It's an easy way to bring attention to it and find out what's going on. I really can't imagine going to HR over a man shifting about in a chair and claiming you know it's his bits he's shifting. My back hurts and I often shift about in a chair and it has nowt to do with my fanny!

It's only - and always - while they're alone. Her instinct is telling her it's unsafe behaviour - as per all our don't-make-waves training to ignore and hope it goes away

The question is, why is your instinct to make excuses for this man that you don't even know?

Maybe because I don't assume everyone is a predator when all they're doing is shifting in a chair? If she feels he's grinding suggestively on the seat then yes she should go to HR but from what she wrote it doesn't sound like that at all. So ya know, I gave my opinion based on what she wrote.

Do you spread your legs as widely as they'll go when getting your back comfortable, Ticketty? Would you do it practically in someone's face at work while demanding they talk to you? Would you do it to only one person and only when there's nobody else around?

I bet you wouldn't. And I bet this isn't about his back. 🙄

Tbh after the previous posts I have reservations about the "as widely as possible".

The very best guide is OP's instinct. As humans - especially as women - we have heightened sensitivity to threat and danger. If in doubt about whether behaviour is predatory or not, go by gut feeling.

But I'd use his "back" as cover to challenge him if you don't want to risk being frank, OP.

"Back troubling you, George?" whenever he does it. "How's your back today, George?" in front of others, to see whether they look surprised. "Oh, George just can't get comfy in his chair, haven't you noticed? It can't just be me..." "Hope your back's not going to play up today, George," as he goes to sit down.

"If it itches mate, it needs washing"